Radian International LLC, P.O. Box 201088, Austin, TX, 78720-1088, USA

This study explores differences in derivatizing reagents and internal standards in opiate analysis. Compounds included were morphine (-D3, -D6), codeine (-D3, -D6), hydromorphone (-D3), hydrocodone (-D3, -D6), and oxycodone (-D3, -D6). In our study we evaluated three derivatives (TFA, TMS, and PPA) and nine internal standards. All samples were analyzed by GC/MS/SIM unextracted for the amount of derivatization as well as for enolization of the ketones.

Although extracted samples have shown otherwise, the results suggested that the derivative with least amount of enolization was TMS using BSTFA with 1% TMCS. The derivative with the most complete derivatization was also TMS. Unfortunately, TMS derivatives of opiates also have more ion interferences. These coincident ions can cause problems on the low and high ends of calibration curves especially with the new cut-off. The derivative that appears to have the fewest interferences is the TFA using TFAA. Overall the internal standards that are more highly labeled provided less contribution to the target drug ions. The unlabeled drug ions also contributed less to higher labeled internal standard ions. This means fewer problems on both ends of the calibration curves.